the following code snippet:

#include <codecvt>
 
namespace lldb_private {
    
    class Editline
    {
    private:
     std::wstring_convert<std::codecvt_utf8<wchar_t>> m_utf8conv;
 
     };
}

g++ -std=c++11 -S 

gives:
wstring-convert.cpp:8:11: error: ‘wstring_convert’ in namespace ‘std’ does not name a template type
      std::wstring_convert<std::codecvt_utf8<wchar_t>> m_utf8conv;

on both linux and darwin.